1. \\(f(x)=2x\\) is order-preserving, \\(f(x)=x^2\\) is not (e.g., \\(-1<0\\), but \\(f(-1)=1>0=f(0)\\)).
2. \\(f(x)=x+2\\) is metric-preserving, \\(f(x)=x/2\\) is not.
3. we can reuse the same functions as in point 1.